a) Field of the Invention
The present invention relates to a device and system which control a projector and more particularly to a device and system which control a projector based on the DMX (Digital Multiplex) protocol.
b) Description of the Prior Art
Nowadays, projection is used widely in places such as a family, a business, an industry, a factory or a movie theater. However, the existing projection device is only equipped with an analogue input port and a digital input port, wherein basic circuit structures thereof are an image control circuit and the projection device, with that analogue and digital signals which are inputted are first processed by the image control circuit, followed by being outputted to the projection device and projected on a screen; therefore, functions thereof are relatively simpler.
The DMX protocol has already been acknowledged and complied with by manufacturers of stage lighting equipment in the world to act as a widely used digital lighting control protocol, meaning that if each controlled fixture unit complies with this protocol, then the digital lighting control can be implemented.
A control signal of the DMX-512 or DMX-512A protocol uses a frame as the unit and each frame can drive at most 512 light loops, also called 512 DMX channels in the entertainment lighting industry. An effective DMX value of each DMX channel is between 0 and 255 and this feature of DMX allows people to implement linear modulation to the light loop by adjusting a light modulation value of DMX, such as the LED (Light Emitting Diode) lighting equipment which is more and more commonly used now. A DMX controller is a kind of device which continuously sends a DMX control signal to the controlled lighting equipment, enabling a stage lighting control engineer to design and compile a lighting control program in advance for each scene of performance, or sections of the DMX control signals. The lighting control program is then stored in each DMX controller and when the performance begins, the lighting control engineer only needs to activate the program, then the lighting equipment will follow the program (DMX signals) to show on the stage according to the previous design, which is simple and convenient in operation. This method of using the DMX protocol to implement the lighting control of the scenes has become more and more popular.